1. Field of the Invention
The present invention relates to a fuel injection device of an internal combustion engine.
2. Description of Related Art
A fuel injection valve for directly or indirectly injecting fuel into a combustion chamber of an internal combustion engine (an engine, hereafter) is publicly known. The fuel injected from the fuel injection valve is mixed with air in an air intake pipe or a combustion chamber and forms combustible mixture with the air. The mixture in the combustion chamber is compressed by a piston. Then, the mixture is ignited by an ignition plug and is combusted.
In the case of such a kind of engine, mixing performance between the fuel injected from the fuel injection valve and the air affects engine performance. Specifically, atomization of the fuel injected from the fuel injection valve is an important factor that affects the engine performance. A technology of disposing a plate, which is formed with multiple injection holes, at a tip end of a nozzle of the fuel injection valve is publicly known as disclosed in Japanese Patent Application Unexamined Publication No. H11-70347 (a patent document 1), for instance. By disposing the plate formed with the multiple injection holes at the tip end of the nozzle, the fuel flowing through a fuel passage formed between a valve member and a valve body is distributed to respective injection holes. Thus, the atomization of the fuel is promoted.
Recent years, regulations such as further reduction of harmful matters (for instance, nitrogen oxides) discharged from the engine have been strengthened. Therefore, the reduction of the harmful matters included in the exhaust gas is required than ever. However, it is difficult for the conventional atomization technology to respond to the recent strengthening of the exhaust gas regulations.
In a fuel injection valve disclosed in the patent document 1, an injection hole is formed in a cylindrical shape in a plate. Since the injection hole is formed in the cylindrical shape, a position for forming a fuel spray can be easily controlled. By arbitrarily adjusting the positions of the multiple injection holes formed in the plate, the fuel spray can be formed in a desired shape. In the case where the injection hole is formed in the cylindrical shape, the fuel injected from one injection hole forms a spray in a rod-like shape. Therefore, further atomization of the fuel is difficult.